Move some files on every dir to a different dir [duplicate]

Question

Possible Duplicate:
How can I move files by type recursively from a directory and its sub-directories to another directory?

I'm quite new to Linux and specially to the shell and all of its commands. My goal is to move some files in every directory to another directory. To be more clear, I have this:

/DIR  
- /dir1  
  - file1  
  - file2  
  - ...  
- /dir2  
  - file1  
  - file2  
  - ...  
- ...  
- /dirn  
  - file1  
  - file2  
  - ... 

What I need is to move all the file1 and file2 into a new dir in its own dir, so that I get something like this:

/DIR  
- /dir1
  - /mydir
      - file1  
      - file2  
  - ...  
- /dir2
  - /mydir
      - file1  
      - file2  
  - ...  

For the sake of the question I have to say that dir names are not like "dir1", "dir2" and so on, but are arbitrary names. Files, however, are always named the same (models.py and wrappers.py). Thanks for your help.
P.S.: I'd really appreciate if you could explain me your answers, in order to learn a bit more about Linux and not just copy-pasting the code.

Answer 1

cd DIR 
for dir in $(find . -maxdepth 1 -mindepth 1 -type d -printf "%f\n" )
do
    cd $dir
    mkdir -p mydir
    mv *.py mydir
    cd ..
done

cd into the top level directory. The find command will find all the files that match the supplied criteria and print them. Maxdepth and mindepth limit the search to files directly under DIR, and type limits the result list to directories. Use a for loop to iterate over each of the directories returned by the find command. cd into each one, create the mydir subdir, move the files into it, then cd back up to DIR so that the next iteration can process the next directory.

If you have any other directories under DIR that don't contain *.py, you can skip them by inserting an if statement right above the cd $dir line:

if [ "$dir" = "skip" -o "$dir" = "whatever" ]; then continue; fi